Influence of soil non-linearity on the dynamic response of high-speed railway tracks

The main objectives of this paper are the evaluation of the relevance of the non-linear behaviour of the soil on the track response and the validation of a methodology, which includes these effects through an equivalent linear analysis. The proposed numerical model is based on 2.5D finite/infinite elements method, coupled with an iterative procedure in order to obtain an agreement between the strain levels and the dynamic properties of the materials. In order to validate the model, the case study of Ledsgard was simulated, and the experimental and numerical results of displacements of the track were compared, considering several circulation speeds for the X2000 train. From the results, it is possible to recognize that the stiffness degradation, function of the strain level, plays a relevant role for the case of high-speed railway lines on soft ground. Moreover, the simulations developed with the proposed methodology provided similar results to those observed, independently of the train speed, contrary to what was obtained when the elastic linear model was used.